1. Prior Art
The prior art appears to be best exemplified by the following patent: Persson, U.S. Pat. No. Des. 244,833 dated 6/28/77.
2. Field of the Invention
Double cavity trays of the general type contemplated by this invention are familiar items of commerce. Such "clam shell" type cartons are popularly used in the packaging of hamburgers and other items sold at fast-food, carryout facilities, for example. One such carton is illustrated in U.S. Pat. No. Des. 244,833 and is conveniently formed from unitary scored blanks of a suitable material such as paper or paperboard folded along fold lines to present a bottom tray portion and a top tray portion hingedly connected at the respective rear walls through a center hinge. Such blanks are assembled into cartons simply by adhering suitable glue tabs to erect the top and bottom tray cavities and then folding the top tray portion over the bottom tray portion via the center hinge on the rear wall.
One problem encountered with such cartons has been their tendency to buckle and prevent easy opening. The construction of such cartons involves a substantial space between the rear wall hinge and the opening feature at the front of the carton. This space, coupled with the somewhat flexible nature of the paperboard, results in a tendency in the carton to flex or fold when the top cover portion is lifted and folded back causing the rear wall to bow outwardly and buckle instead of readily folding back on the center hinge. It often happens that further attempts to lift the top cover while the carton is in such buckled and/or outwardly bowed condition results in tearing of the top cover at the center hinge thus impairing and even destroying in some instances any reclosure feature that may be present.
This invention relates to blanks and cartons constructed therefrom of the double cavity, clam shell type. A particular object of the invention is the provision of a construction that is easily opened because it is free of buckling and/or bowing and that is recloseable after opening.